Seiko 0680A – Technical Guide (High Quality)

The Seiko 0680A is an important quartz analog movement introduced in the early 1970s as part of Seiko’s rapid expansion into quartz watch technology following the success of the pioneering 0674A. The 0680A movement powers the Seiko Quartz Astron 38SQ, an evolution of the original Astron model. It brought improvements in size, energy efficiency, and functionality while maintaining exceptional accuracy, marking Seiko’s continued leadership in quartz innovation.

1. Technical Specifications

2. Key Features

• Analog quartz movement with sweeping seconds hand

• Date complication with quickset function via crown

• High accuracy of ±5 seconds per month, exceptional for its era

• 14-jewel movement for durable and smooth mechanical parts

• Integrated circuit and transistorized electronics control timekeeping and motor

• Step motor drives gear train precisely with pulses from the quartz oscillator

• Smaller and more refined than the original 0674A movement

• Battery powered, featuring a mercury battery (now obsolete)

3. Operation & Time Setting

Time Setting:

• Pull crown to the second position

• Rotate to adjust hour and minute hands

• Push crown back to resume running

Date Setting:

• Pull crown to the first position

• Rotate clockwise to quickly advance the date

• Avoid setting date between 9 PM and 2 AM to protect calendar gears

The seconds hand does not hack and continues running during time adjustment.

4. Movement Architecture

• Quartz crystal oscillator at 8,192 Hz frequency

• Electronic integrated circuit (IC) for signal processing and motor control

• Stepper motor converting electrical impulses to mechanical rotation

• Mechanical gear train driving hour, minute, second, and date wheels

• Date quickset mechanism integrated into the keyless works

• Jewelled bearings for critical friction points to improve durability

• Battery compartment designed for a mercury-type battery (no longer produced)

5. Servicing and Maintenance

• Battery replacement is essential; modern substitutes with proper voltage are required

• Movement servicing requires expertise in both quartz electronics and mechanical components

• Cleaning, lubrication, and adjustment follow standard watchmaking practices, with caution for sensitive electronics

• Replacement of IC or quartz crystal is highly specialized and usually requires movement replacement

6. Common Issues & Troubleshooting

7. Historical Significance

The Seiko 0680A was a critical advancement building on the 0674A quartz revolution, showcasing:

• Improved compactness and efficiency

• Continued leadership in quartz technology during the 1970s

• The foundation for many subsequent Seiko quartz calibers

• A symbol of Seiko’s innovation and technical prowess in the quartz era

8. Conclusion

The Seiko 0680A is a landmark quartz movement that combines precision engineering, advanced electronics, and mechanical craftsmanship. It powers a key successor to the original Quartz Astron, delivering top-tier accuracy and reliability for its time. Though complex and requiring expert servicing, the 0680A remains a treasured movement for collectors and horological historians, representing Seiko’s pioneering role in the quartz watch revolution.